This application failed to start because it could not find or load the Qt platform plugin “xcb”
This error message is because either the XCB QT5 module can’t be found, or the module can’t be loaded because one of its library dependencies is missing. I ran into this issue when installing VLC from Fedora 24 repositories using DNF. Running VLC from the shell gave me some error output about XCB not being found.
Create a new “platforms” link
It’s possible that the modules aren’t being found because of a missing link. If /usr/bin/platforms does not exist, create a new link to the modules.
ln -sf /usr/lib64/qt5/plugins/platforms/ /usr/bin/platforms
Check broken dependencies
When you start your application after creating the link above, you may get the same error but this time also showing the it DOES detect the XCB module.
Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, xcb.
This means that the module is detected but unable to load. To check which dependencies are missing, we need to check the module using LDD.
ldd /usr/bin/platforms/libqxcb.so | grep "not found"
This command will output something like “libxkbcommon-x11.so.0 => not found” if there’s a broken dependency. In this case, running “dnf install libxkbcommon-x11” was all that was needed to completely fix VLC in Fedora 24.